(2R,8aR,12R)-1,1,4β,12-Tetramethyl-1,2,3,3aα,4,4aβ,5,6,7,8,9,10-dodecahydro-10aH-2β,3β-epoxy-7β,8aβ-ethanobenzo[f]azulene-4,9α,10β,10aβ,12-pentol